While most people appreciate the importance of physical fitness, many have difficulty finding the motivation required to maintain a regular exercise program. Some people find it particularly difficult to maintain an exercise regimen that involves continuously repetitive motions, such as running, walking and bicycling. Devices for tracking a user's activity may offer motivation in this regard, providing feedback on past activity, and encouragement to continue with an exercise routine in order to meet various exercise goals.
However, certain exercise metrics for athletes are assessed in formal lab-based settings, and using cumbersome equipment to monitor an individual while he/she exercises at a fixed location (e.g. on a treadmill or stationary bike). As such, these exercise metrics may not be readily available to the general population. Further, reliance on natural phenomena, such as simply correlating energy output to predictive and/or prescriptive outcomes, is not only inaccurate, but of limited use. For example, merely correlating energy expenditure, e.g., calories, to work, cannot be used to predict one or more valuable parameters, including for example, critical intensity and/or an anaerobic work capacity of an individual. Therefore, improved systems and methods to address at least one or more of these shortcomings in the art are desired.